Reset mechanism for use in electric device equipped with microcomputer and resetting method

ABSTRACT

Disclosed is a reset mechanism for use in an electric device equipped with a microcomputer having a reset circuit associated therewith. The insulating housing of the electric device has a small through hole made therein, and the chassis of the electric device has a small through hole made in alignment with the small through hole of the insulating housing. The reset terminal of the reset circuit is placed behind the small through hole of the chassis of the electric device. The microcomputer can be reset simply by inserting a metal rod in the two through holes as far as the reset circuit.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a reset mechanism to be used in resetting a microprocessor or such like installed in an electric device.

[0003] 2. Related Arts

[0004] Nowadays there have been a variety of electronic devices each having various functions. Such an electronic device has a microcomputer installed therein for controlling its numerous electric circuits. The computer, however, cannot work correctly when being supplied with incorrect signals or when something is wrong in an associated electric circuit. It may be possible that such malfunctions be caused by certain surrounding factors.

[0005] To recover the microcomputer from such defective condition, it is necessary that the microcomputer be made to stop working. For this purpose the microcomputer is equipped with a reset switch. Such a reset switch is designed to be used exclusively for resetting the microcomputer. It, however, is not used often, and therefore, providing the microcomputer with such an extra switch for exclusive use is undesirable from the angle of manufacturing cost.

[0006] Hitherto, a variety of reset switches have been proposed as for instance, follows: Japan Patent 06-76689(A) discloses a “reset switch”; and Japan Patent 05-120952(A) discloses a “reset switch for electric equipment”. These reset switches are simple in structure comparing with those which were used before, but they are still designed to be exclusive for use in resetting.

SUMMARY OF THE INVENTION

[0007] In view of the above one object of the present invention is to provide a reset mechanism for resetting an electric circuit or electronic device such as a microcomputer without the necessity of providing it with an extra switch used exclusively for the purpose of resetting.

[0008] To attain this object according to the present invention, a reset mechanism for use in an electric device equipped with a microcomputer having a reset circuit associated therewith, is characterized in that an insulating housing of the electric device has a small through hole made therein; a chassis of the electric device has a small through hole made in alignment with the small through hole of the insulating housing; and that a reset terminal of the reset circuit is placed behind the small through hole of the chassis of the electric device.

[0009] In place of the chassis of the electric device, a metal casing or mount of a selected part of the electric device may have a small through hole made in alignment with the small through hole of the insulating housing.

[0010] Another object of the present invention is to provide a method for resetting an electric circuit or electronic device such as a microcomputer without recourse of a reset switch used exclusively for the purpose.

[0011] To attain this object according to the present invention, a method of resetting an electric device equipped with a microcomputer having a reset circuit associated therewith, comprises the steps of: making a small through hole in an insulating housing of the electric device; making a small through hole in a chassis of the electric device to be in alignment with the small through hole of the insulating housing and in alignment with a reset terminal of the reset circuit, which is placed behind the small through hole of the chassis of the electric device; and inserting an electrically conductive rod in the small through holes in the insulating housing and the chassis of the electric device to touch the reset terminal, thereby making an electric connection between the reset terminal and the chassis of the electric device.

[0012] Other objects and advantages of the present invention will be understood from the following description of a reset mechanism according to one embodiment of the present invention, which is shown in accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

[0013]FIG. 1 shows, in section, a reset mechanism according to the present invention; and

[0014]FIG. 2 is a wiring diagram of the reset mechanism.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0015]FIG. 1 shows a reset mechanism disposed at the front part of an electric device equipped with a microcomputer having a reset circuit 4 associated therewith. The reset circuit 4 is built in a printed circuit board 3. The insulating housing of the electric device is made of a synthetic resin material, and it has a small through hole 6 made in its front plate 1. The chassis 2 of the electric device has a small through hole 8 made in its front rise 7. The small through hole 8 is made in alignment with the small through hole 6 of the front plate 1 of the insulating housing.

[0016] The reset circuit 4 is placed behind the small through hole 8 of the chassis 2 of the electric device. When it is desired that the micro computer is reset, an electrically conductive rod 5 is inserted in the small through holes 6 and 8 in the insulating housing and the chassis 2 to touch the reset circuit 4, thereby making an electric connection between the reset circuit 4 and the chassis 2, which is grounded.

[0017] In this particular embodiment, the through hole 6 is made in the front plate 1 of the insulating housing, but the through hole 6 can be made in the rear, either side or bottom plate of the insulating housing, provided that access to the reset circuit 4 be permitted via the small through holes 6 and 8 in the insulating housing and the chassis 2. The electrically conductive rod 5 may be a nail, pin or a short wire.

[0018] Usually a microcomputer or a reset signal generator compares a certain voltage from an associated voltage regulator with a predetermined reference voltage all the time to generate a reset signal when unusual working condition is detected in terms of the result of comparison. When an electric connection is made between the metal chassis 2 and the reset circuit 4 by the electrically conductive rod 5, the voltage appearing at a given point in the reset circuit 4 changes to provide a reset signal for resetting the microcomputer.

[0019] Referring to FIG. 2, the voltage regulator 9 is connected to the microcomputer 10, which is connected to the reset circuit 4. The voltage regulator 9 and the microcomputer 10 are connected to loads 11 and 12, which are associated with an electric apparatus. As shown in the drawing, a voltage V_(b) is applied to the microcomputer 10 via the voltage regulator 9, and the metal chassis 2 is grounded.

[0020] When the microcomputer 10 is reset, a metal rod 5 is inserted in the through hole 8 of the chassis 2 until it reaches the reset circuit 4, and at the same time, the metal rod 5 touches the metal chassis 2, thereby causing the voltage at a certain point in the reset circuit 4 to change. As a result a reset signal appears to reset the microcomputer 10.

[0021] A through hole 8 is made in the front rise of the chassis 2. In stead, the through hole 8 may be made in an electrically conductive part of the electric device other than the chassis 2.

[0022] The reset mechanism according to the present invention provides the following advantages:

[0023] no extra switch is required for resetting. In resetting the microcomputer it suffices that a metal rod is inserted in two series-arranged through holes as far as the reset circuit. The resetting mechanism is simple in structure, compared with a conventional reset switch, and accordingly the manufacturing cost can be reduced. 

What is claimed is:
 1. A reset mechanism for use in an electric device equipped with a microcomputer having a reset circuit associated therewith, characterized in that an insulating housing of the electric device has a small through hole made therein; a chassis of the electric device has a small through hole made in alignment with the small through hole of the insulating housing; and that a reset terminal of the reset circuit is placed behind the small through hole of the chassis of the electric device.
 2. A reset mechanism according to claim 1, wherein in place of the chassis of the electric device a metal casing or mount of a selected part of the electric device has a small through hole made in alignment with the small through hole of the insulating housing.
 3. A method of resetting an electric device equipped with a microcomputer having a reset circuit associated therewith, characterized in that it comprises the steps of: making a small through hole in an insulating housing of the electric device; making a small through hole in a chassis of the electric device to be in alignment with the small through hole of the insulating housing and in alignment with a reset terminal of the reset circuit, which is placed behind the small through hole of the chassis of the electric device; and inserting an electrically conductive rod in the small through holes in the insulating housing and the chassis of the electric device to touch the reset terminal, thereby making an electric connection between the reset terminal and the chassis of the electric device. 